43 Spanish Chamber

[Steveu]

I acquired a Argentine 1879 RB with a mint bore. I did a cast form mid-case up to .9" into the barrel. Groove diameter is .441", the neck seems short at .225" and the shoulder length is .150". I did a cast of the Lee sizing die to see what it was and the shoulder length is .220", which from what I have read is the correct length. So the question is, what chamber do I have?
Cheers,
Steve

[Don McDowell]

I would guess you have a 43 Spanish chamber. A lot of those old guns have pretty inconsistent chambers, and bore dimensions. It'll probably shoot pretty well once you get the cases fire formed, resizing the cases most likely won't be necessary with a bullet correct for the bore. Probably going to have to order a bullet mould from Accurate to get one that will drop you a .441 diameter bullet, as I believe the Lyman bullet drops at .439.

[Steveu]

I checked the dimensions against what is in the "Handloaders Manual to Cartridge Conversions" and it is a 11.15X58r. I was looking at the dimensions that were online at Load Data and they show what I think is the wrong dimension for the cartridge. They list the cartridge as the "11.5x57R/ .43 Spanish Reformado" and the diagram is labeled 11.15x58R. I am still confused by the Lee die shoulder length. It should not matter, because I am going to be using new brass and neck sizing.

Cheers,
Steve